WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Access Right: Open AccessSubject: search.filters.subject.Gravitation

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 26
    Citation - Scopus: 26
    Induced Affine Inflation
    (American Physical Society, 2018) Azri, Hemza; Demir, Durmuş Ali; Azri, Hemza; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Induced gravity, metrical gravity in which gravitational constant arises from vacuum expectation value of a heavy scalar, is known to suffer from Jordan frame vs Einstein frame ambiguity, especially in inflationary dynamics. Induced gravity in affine geometry, as we show here, leads to an emergent metric and gravity scale, with no Einstein-Jordan ambiguity. While gravity is induced by the vacuum expectation value of the scalar field, nonzero vacuum energy facilitates generation of the metric. Our analysis shows that induced gravity results in a relatively large tensor-to-scalar ratio in both metrical and affine gravity setups. However, the fact remains that the induced affine gravity provides an ambiguity-free framework.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 3
    Affine Dynamics With Torsion
    (Springer Verlag, 2016) Gültekin, Kemal; Gültekin, Kemal; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this study, we give a thorough analysis of a general affine gravity with torsion. After a brief exposition of the affine gravities considered by Eddington and Schrödinger, we construct and analyze different affine gravities based on the determinants of the Ricci tensor, the torsion tensor, the Riemann tensor, and their combinations. In each case we reduce equations of motion to their simplest forms and give a detailed analysis of their solutions. Our analyses lead to the construction of the affine connection in terms of the curvature and torsion tensors. Our solutions of the dynamical equations show that the curvature tensors at different points are correlated via non-local, exponential rescaling factors determined by the torsion tensor.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 6
    Surfactant Adsorption and Marangoni Flow in Liquid Jets. 2. Modeling
    (American Chemical Society, 2004) Weiss, Michael; Darton, Richard C.; Battal, Turgut; Bain, Colin D.; 01. Izmir Institute of Technology
    This paper is concerned with the interfacial behavior of surfactant solutions on short time scales. A gravity-driven laminar liquid jet is used to create a rapidly expanding liquid surface, which exposes the surfactant solution to highly nonequilibrium conditions. This expansion causes the surface tension to differ locally from its equilibrium value, generating a (Marangoni) shear stress that acts on the jet surface and retards the surface acceleration. A theory for the flow very near the nozzle shows that the cube-root dependence of the surface velocity on the distance traveled is altered through the adsorption of surfactant. In a boundary-layer treatment, both the surface velocity and the surface concentration increase linearly from the nozzle exit over a short distance, which we term the detachment region. The length of the detachment region is found to vary with the bulk concentration raised to the power 3/2. A numerical model of the surfactant adsorption process in the jet has been developed within the framework of the CFD code FIDAP. The numerical solution confirms the general features of the theory and shows that the maximum reduction in surface velocity occurs very close to the nozzle exit, except at high concentrations. A comparison with experiments on C16TAB at concentrations below the critical micelle concentration, which are described in part 1 of this series of papers, shows good agreement.